Provisional  Draft ] 

HARVARD  UNIVERSITY 


OUTLINE  OF  REQUIREMENTS 


METEOROLOGY 


INTENDED  FOR  USE  IN  PREPARING  STUDENTS 
FOR  HARVARD  COLLEGE  AND  THE 
LAWRENCE  SCIENTIFIC  SCHOOL 


CAMBRIDGE 

1S97 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/outlineofrequireOOharv 


HP  ^ <\% 

Provisional  Draft.] 


OUTLINE  OF  REQUIREMENTS  IN  METEOROLOGY. 


Object  of  this  Pamphlet.  — The  present  outline  is  intended  to  serve 
as  an  aid  to  teachers  who  wish  to  prepare  their  pupils  for  the  exam- 
ination in  Elementary  Meteorology  given  by  Harvard  College  and 
the  Lawrence  Scientific  School.  The  suggestions  here  made  will 
suffice  to  indicate  the  essential  points  which  a higli-school  course  in 
this  subject  should  cover,  and  on  which  students  are  expected  to  be 
prepared  when  they  come  up  for  examination.  It  is  not  intended 
that  this  outline  shall  be  rigidly  adhered  to,  but  that  the  teacher 
shall  use  his  discretion  in  changing  the  order  of  treatment  here  sug- 
gested, and  in  extending  the  course  as  he  may  see  fit.  The  outline 
is  to  be  for  the  present  considered  to  a large  degree  experimental. 
This  must  inevitably  be  the  case  until  it  has  been  tested  by  actual 
use  in  schools.  In  the  light  of  the  experience  which  will  thus  be 
gained,  it  will  probably  be  possible  shortly  to  publish  a revised  out- 
line. Teachers  are  requested  to  communicate  their  views  freely 
regarding  the  general  scheme  of  the  course,  or  concerning  any  of  the 
individual  subjects  suggested  for  study. 

Object  of  the  Course.  — The  scheme  of  work  here  proposed  corre- 
sponds quite  closely  to  the  plan  followed  in  the  course  in  Elementary 
Meteorology  (Geology  B)  in  Harvard  College.  Careful  and  syste- 
matic work  in  meteorology,  of  the  character  here  indicated,  will  be 
found  to  give  the  student  good  training  in  scientific  methods  of 
investigation,  and  to  make  him  to  some  extent  a thinker  and  investi- 
gator on  his  own  account.  It  will  also  furnish  a basis  on  which 
later  studies  in  more  advanced  meteorology  may  be  continued.  This 
course,  however,  should  give  so  rational  and  systematic  a knowledge 
of  the  leading  facts  concerning  the  atmosphere,  the  weather  and  its 
changes,  and  the  physical  laws  underlying  these  changes,  that  it  will 
afford  to  those  who  do  not  pursue  the  subject  further  a useful  and 
well-rounded  part  of  their  education. 


4 


Time  necessary  for  the  course.  — The  course  should  occupy  at 
least  three  hours  a week,  in  addition  to  supplementary  hours  for 
study  and  observation,  for  half  a school  year.  It  is,  however, 
recommended  that  the  course  should  be  extended  through  a whole 
year,  at  the  rate  of  an  hour  and  a half  a week  (with  supplementary 
hours  as  above),  in  order  to  give  opportunity  for  observation  through 
autumn,  winter,  and  spring.  It  may  in  this  form  be  combined  with 
a course  in  astronomy,  which  is  advantageously  arranged  in  the  same 
manner. 

The  teacher’s  share  in  the  work.  — The  work  of  the  teacher  may 
be  indicated  under  the  following  headings  : Instruction  in  the  use  of 
instruments  ; selection  of  subjects  for  observation ; suggestions  for 
keeping  note-books ; guidance  in  the  discussion  of  observations ; 
presentation  of  the  larger  and  more  general  relations  of  the  various 
subjects  studied,  such  as  cannot  be  learned  without  the  aid  of  text- 
books or  lectures.  The  teacher  should  encourage  the  students  to 
discover  for  themselves,  as  far  as  possible,  the  facts  and  generaliza- 
tions that  follow  from  their  observations.  Useful  practice  in  English 
composition  may  be  had  by  requiring  careful  formulation  of  these 
results.  There  may  be  need  of  much  assistance  from  the  teacher 
at  times,  especially  near  the  beginning  of  the  course ; but  as  the 
work  becomes  more  familiar,  the  students  should  be  left  more  and 
more  to  themselves,  and  the  teacher  should  confine  himself  to  plan- 
ning the  order  of  observations,  to  giving  instruction  in  such  subjects 
as  are  not  illustrated  by  local  observations,  and  to  promoting  the 
discussion  of  the  results  that  have  been  obtained  by  the  class. 

The  teacher’s  preparation  for  this  work  should  include  a careful 
study  of  the  general  subject,  such  as  may  be  based  upon  the  reference 
book,  Davis’  Elementary  Meteorology,  supplemented  by  additional 
reading,  and  by  practice  in  the  use  of  the  ordinary  meteorological  in- 
struments and  in  the  construction  and  interpretation  of  daily  weather 
maps. 

Previous  preparation  of  the  student.  — The  study  of  geography  in 
the  grammar  school  or  early  years  of  the  academy  should  have 
familiarized  the  student  with  the  thermometer,  the  rain-guage,  and 
the  wind-vane,  and  their  use  in  simple  weather  records ; weather 
maps  and  their  elementary  interpretation ; the  observational  deter- 
mination of  the  variation  in  the  sun’s  noon  altitude  and  in  the  length 


5 


of  the  day  and  night  with  the  seasons ; and  the  general  distribution 
of  heat  belts,  prevailing  winds,  and  rainy  and  dry  regions  over  the 
world.  If  these  subjects  have  not  been  previously  taught,  it  will 
be  impossible  to  present  the  work  in  meteorology  as  here  outlined 
without  a serious  addition  to  the  time  allotted  to  it. 

In  the  high  school,  or  later  years  of  the  academy,  physics  and 
geometry  should  precede  meteorology. 

Note-Books.  — Each  student  should  keep  a note-book  in  which 
careful  record  is  made  of  the  instruments  used,  of  the  conditions 
of  their  exposure,  and  of  the  observations  made.  Whenever  a 
special  problem  involves  the  combination  of  records  made  by 
different  observers,  the  source  of  the  combined  records  should  be 
clearly  indicated.  The  records  should  be  duly  tabulated  and  dis- 
cussed. Inferences  drawn  from  the  observations  must  be  separately 
entered  on  pages  opposite  to  those  bearing  the  observations.  Dis- 
tinction must  be  made  between  the  student’s  own  inferences  and 
those  that  have  been  suggested  by  others.  Care  should  be  given  to 
the  form  of  all  verbal  statements  in  which  results  are  embodied. 

The  notes  should  not  be  crowded.  Some  space  should  be  left 
between  successive  topics,  and  each  topic  should  be  marked  with  a 
prominent  heading.  A summary  of  the  various  topics,  which  will  be 
necessarily  encountered  in  a somewhat  unsystematic  order  during  the 
progress  of  the  observational  work,  should  be  finally  made  according 
to  some  systematic  scheme.  An  index  should  be  appended. 

Examination.  — The  candidate  presenting  meteorology  as  an  ad- 
mission subject  will  be  required  to  take  both  a written  and  a labora- 
tory or  practical  examination.  The  written  examination  may  test 
his  understanding  of  observational  methods  appropriate  to  the  sub- 
ject, but  will  call  chiefly  for  a knowledge  of  facts  and  principles. 
The  laboratory  or  practical  examination  will  test  his  skill  in  observa- 
tion as  well  as  his  grasp  of  principles.  This  examination  can  be 
taken  in  Cambridge  only ; for  those  who  are  examined  elsewhere  in 
June,  it  will  be  postponed  to  September.  It  may -include  the  use  of 
instruments,  the  discussion  of  observations,  and  the  construction  and 
interpretation  of  weather  maps  and  climatic  charts. 

The  candidate  will  be  required  to  present  at  the  time  of  the  labora- 
tory or  practical  examination,  the  original  note-book  in  which  he 
recorded,  with  dates,  the  steps  and  results  of  the  observations  which 


6 


he  made  at  school.  This  book  must  bear  the  endorsement  of  the 
teacher,  certifying  that  the  notes  are  a true  record  of  the  pupil’s 
work.  The  note-book  is  required  as  proof  that  the  candidate  has 
formed  the  habit  of  keeping  a full  and  intelligible  record  of  his  work 
through  an  extended  course  of  observational  study,  and  that  his  work 
has  been  of  a satisfactory  character ; but  greater  weight  will  be  given 
to  the  practical  or  laboratory  examination  than  to  the  note-book  in 
determining  the  candidate’s  attainment. 

This  pamphlet  has  been  prepared  under  the  authority  of  the 
Department  of  Geology  and  Geography  of  Harvard  University. 
Teachers  who  wish  to  make  any  suggestions  or  to  ask  any  questions 
in  regard  to  the  work  or  the  examination  should  address,  — 

until  February  1,  1898,  W.  M.  Davis, 

after  February  1,  1898,  Robert  DeC.  Ward, 

Harvard  University, 

Cambridge,  Mass. 

EQUIPMENT. 


Instruments.  Cost. 

Exposed  thermometer  (with  brass  support)  . . $2.50-  2.75 

Maximum  and  minimum  thermometers 7.75-  8.25 

Wet  and  dry  thermometers . 5.00-  6.50 

Sling  psychrometer 5.00 

Rain  gauge 5.25 

Soil  thermometer 4.50-19.00 

Wind  vane 10.00 

Anemometer 23.00-25.00 

Anemometer  register 24.00-35.00 

Barometer  (aneroid) 14.00-16.00 

Barometer  (mercurial) 30.00 


[These  instruments  can  all  be  procured  of  H.  J.  Green, 

1191  Bedford  Avenue,  Brooklyn,  N.  Y.] 

Thermograph  (Richard  Freres,  Paris)  . $30.00  (without  duty) 
Barograph  (Richard  Freres,  Paris)  . . 27.60  (without  duty) 

[These  two  instruments  can  be  procured  through  Glaenzer 
Freres  and  Rheinboldt,  26  Washington  Place,  New  York, 

N.  Y.] 

Note.  — These  instruments,  while  all  desirable,  are  not  all  necessary.  The 
sling  psychrometer  (which  may  be  used  as  an  ordinary  sling  thermometer),  the 
maximum  and  minimum  thermometers,  the  rain-gauge,  and  some  form  of  baro- 
meter are  essential.  A wind  vane  on  a neighboring  building  may  save  the 


expense  of  buying  such  an  instrument.  The  other  instruments,  as  above  sug- 
gested, should  be  added  if  possible.  The  instrument  shelter,  in  which  the  ther- 
mometers and  thermograph  should  be  exposed,  may  advisably  be  built  outside  of 
one- of  the  windows  of  the  school  building. 

Books , etc. 

Davis  : Elementary  Meteorology.  Ginn,  Boston,  1895.  $2.50. 

Note. — There  is  no  text-book  covering  the  course  as  here  described,  but 
this  book  will  be  found  necessary  as  a reference  book  in  the  non-observational 
part  of  the  work. 

Instructions  to  Voluntary  Observers. 

Instructions  for  Use  of  Maximum  and  Minimum  Thermometers. 

Instructions  for  Use  of  the  Rain  Gauge. 

Barometers  and  the  Measurement  of  Atmospheric  Pressure. 

Instructions  for  Obtaining  and  Transcribing  Records  from  Recording  Instru- 
ments. 

Note.  — These  pamphlets,  all  issued  by  the  U.  S.  Department  of  Agriculture, 
Weather  Bureau,  and  obtainable  on  application  to  the  Chief  of  the  Weather 
Bureau,  Washington,  D.  C.,  will  be  found  the  best  guides  in  making  observa- 
tions, the  care  of  instruments,  etc. 

Daily  weather  maps,  issued  from  the  nearest  station  of  the  Weather 
Bureau,  and  sent  free  of  charge  to  schools,  are  a necessary  part  of 
the  equipment  in  this  course.  The  Monthly  Weather  Review  (cost- 
ing 10  cents  a number),  the  Bulletins  and  other  publications  of  the 
Weather  Bureau,  which  may  be  secured  from  the  Chief  of  the 
Weather  Bureau,  as  above,  and  the  various  publications  of  the  local 
State  Weather  Services,  will  also  prove  useful. 

Other  publications  which  the  teacher  may  find  it  helpful  to  consult 
are  the  following  : — 

Greely  : American  Weather.  Dodd,  Mead  and  Co.,  New  York,  1888. 

Scott:  Elementary  Meteorology.  International  Scientific  Series,  London, 
1889. 

Abercrombie:  Weather.  International  Scientific  Series,  Appleton,  N.  Y., 
1887. 

Waldo:  Elementary  Meteorology.  American  Book  Co.,  New  York,  1897. 

Russell:  Meteorology.  Macmillan,  New  York,  1895. 

Hazen’s  Meteorological  Tables.  Washington,  1888. 

Smithsonian  Meteorological  Tables.  Smithsonian  Institution,  Washington, 
189-. 


8 


OBSERVATIONS. 

Observational  work  in  meteorology  should  include  a considerable 
variety  of  the  subjects  given  in  the  list  below,  but  it  is  not  expected 
that  any  one  scholar  can  accomplish  all  that  is  here  outlined.  Ex- 
amples should  be  selected  from  the  list,  as  opportunity  offers,  so 
that  each  scholar  shall  acquire  a personal  familiarity  with  at  least 
fifteen  problems,  not  less  than  two  being  taken  from  each  of  the 
seven  headings  given  below. 

Few  of  the  problems  here  suggested  call  for  continuous  routine 
observation  at  fixed  hours ; they  require,  on  the  other  hand,  an 
intelligent  examination  of  ordinary  weather  phenomena  with  special 
reference  to  discovering  their  explanation.  In  most  of  the  problems, 
a small  number  of  observations  will  suffice.  Much  time  may  be  saved 
by  cultivating  a habit  of  promptly  attacking  the  work  in  hand.  Under 
the  supervision  of  the  teacher,  different  problems  may  be  assigned 
to  the  several  members  of  a class  ; or  several  scholars  may  work  on 
different  parts  of  the  same  problem,  exchanging  records  in  order  to 
save  time.  It  is  expected  that  all  the  scholars  will  have  a general 
knowledge  of  the  results  which  have  been  obtained  from  the  observa- 
tions made  by  the  other  members  of  their  class.  The  teacher  will 
use  his  discretion  in  arranging  the  order  of  the  problems,  and  in 
selecting  those  that  are  best  suited  to  the  season  in  wffiich  the  work 
’S  done,  to  the  locality  in  which  the  school  is  situated,  and  to  the 
facilities  and  apparatus  at  command.  The  variety  of  accessible 
problems  decreases  in  city  schools,  but  much  may  be  done  there,  as 
well  as  in  village  or  country  schools. 

The  essence  of  the  observational  work  does  not  lie  in  the  perform- 
ance of  specified  tasks,  rigidly  defined  and  alike  for  all  schools,  but 
rather  in  the  cultivation  of  a habit  of  scientific  inquiry  by  the  practi- 
cal study  of  atmospheric  phenomena.  The  real  nature  of  these 
phenomena  becoming  known  by  actual  observation,  rapid  advance 
may  be  made  in  knowledge  concerning  the  distribution  of  similar 
phenomena  by  means  of  the  non-observational,  or  text-book  por- 
tion of  the  course.  It  is  believed  that  by  a judicious  combination 
of  these  two  kinds  of  study,  the  advantages  of  both  may  be  pre- 
served, while  the  disadvantages  of  slow  progress  through  purely 
inductive  work,  and  unsound  progress  through  purely  didactic  work 
may  be  avoided. 


9 


I.  TEMPERATURE. 

(Instructions,  12-26.  Davis,  17-42,  56-61.)* 

The  temperature  of  the  air,  obtained  by  the  sling  thermometer 
(supplemented  by  maximum  and  minimum  thermometers  and  thermo- 
graph, if  available)  should  be  determined  under  a variety  of  con- 
ditions ; for  example,  close  to  the  ground,  and  at  different  heights 
above  the  ground ; at  different  hours,  day  and  night ; in  different 
seasons ; in  sunshine  and  shade ; during  wind  and  calms ; in  clear 
and  cloudy  weather,  in  woods  and  in  the  open ; over  bare  ground, 
grass,  or  snow  ; on  hills  and  in  valleys.  There  should  also  be  obser- 
vations of  the  temperature  of  ground  and  of  snow,  at  the  surface  and 
at  slight  depths  beneath  the  surface,  under  different  weather  condi- 
tions and  in  different  seasons. 

The  data  thus  determined  will  enable  the  student  to  investigate  a 
number  of  problems,  such  as  the  following  : — 

a.  The  mean  temperature  of  a day  or  of  several  days,  and  the 
variation  of  the  mean  with  changes  of  weather  and  of  season  (Davis, 
61,  62). 

b.  The  diurnal  range  of  temperature  under  different  conditions  and 
at  different  heights  above  the  ground  (Davis,  27,  28,  30,  42,  134, 
155,  243). 

c.  Changes  of  temperature  in  the  lower  air  and  their  control  by 
the  condition  of  the  ground,  the  movement  of  the  air,  etc.  (Davis, 
26-28,  30-34,  316,  317.) 

d.  Vertical  temperature  gradients  and  inversions  of  temperature 
(Davis,  27-28,  34,  32,  138,  139,  156,  158,  243-246,  317). 

e.  Cyclonic  and  anticyclonic  changes  of  temperature  (Davis,  27, 
30,  42,  134,  155,  218,  311,  333). 


* These  references  are  to  “ Instructions  to  Voluntary  Observers  ” and  to  Davis’  “ Elementary 
Meteorology.”  The  references  are  intended  as  guides  for  the  teacher. 


10 


II.  WINDS. 

(Instructions,  49-54.  Davis,  93-99.) 

The  direction  and  velocity  (or  estimated  strength)  of  the  wind 
should  be  determined  at  different  hours,  under  different  conditions 
of  weather,  and  in  different  seasons.  These  observations  will  lead 
to  the  following  problems  : — 

a.  The  prevailing  direction  and  mean  velocity  of  different  periods 
of  several  days  each  (Davis,  98). 

b.  The  diurnal  variation  of  velocity  in  fair  weather  (Davis,  41 , 132). 

c.  The  variations  in  direction  and  velocity  due  to  cyclones  and 
anticyclones,  as  shown  on  the  weather  maps  (Davis,  183,  215, 
226-247). 

d.  The  correlation  of  wind  and  temperature,  as  suggested  in  I,  e. 

III.  HUMIDITY,  DEW,  AND  FROST. 

(Instructions,  27,  49-54,  71-80.  Davis,  146-150.) 

The  humidity  of  the  air,  as  determined  by  wet  and  dry  bulb  ther- 
mometers, and  the  occurrence  or  absence  of  dew  or  frost  should  be 
studied  together.  Observations  should  be  made  at  different  hours, 
in  different  kinds  of  weather,  and  in  different  seasons.  From  these, 
the  following  problems  may  be  solved  : — 

a.  Diurnal  variation  of  relative  humidity  under  different  condi- 
tions (Davis,  152). 

b.  Relation  of  absolute  and  relative  humidity  to  the  direction  of 
the  wind,  and  thus  to  cyclones  and  anticyclones  (Davis,  230-247). 

c.  The  formation  of  dew,  as  dependent  on  the  temperature  and 
humidity  of  the  air ; the  exposure  and  condition  of  the  ground  ; and 
on  the  condition  of  the  sky  (clear,  fair,  or  cloudy)  ; and  the  vertical 
temperature  gradient  (Davis,  154-157). 

d.  The  formation  of  dew  as  dependent  on  the  movement  of  the  air, 
and  thus  on  cyclonic  and  anticyclonic  controls  (Davis,  154-156). 

e.  The  formation  of  frost,  as  dependent  on  similar  conditions ; 
especial  attention  being  paid  to  the  relation  of  frost  and  inversions 
of  temperature,  and  to  the  frequency  of  frost  on  open  or  sheltered 
surfaces,  on  hills  or  in  valleys,  and  on  the  lower  and  upper  branches 
of  shrubs  (Davis,  156-158). 


11 


IV.  CLOUDS  AND  UPPER  AIR  CURRENTS. 

(Instructions,  57.  Davis,  119,  181-182). 

The  form  ancl  movement  of  clouds  should  be  observed  at  different 
hours,  in  different  weather  conditions,  and  in  different  seasons. 
These  observations  should  be  made  with  a horizontal  mirror,  fitted 
with  a bar  and  graduated  scale.  They  lead  to  the  following  prob- 
lems : — 

a.  The  typical  cloud  forms  and  their  changes  (Davis,  177-179). 

b.  The  prevailing  direction  and  average  velocity  of  cloud  move- 
ments for  different  periods  and  especially  for  different  weather  con- 
ditions. Lower  and  upper  clouds  should  be  separated  in  this  study 
(Davis,  119,  172,  181,  182). 

c.  Correlation  of  cloud  form  and  movement  with  surface  winds, 
with  cyclones  and  anticyclones,  and  with  weather  changes  (Davis, 
213,  219,  228). 

d.  The  use  of  clouds  as  weather  prognostics  (Davis,  330). 


V.  PRECIPITATION. 

(Instructions,  43-49.  Davis,  285-291.) 

The  quantity  and  rate  of  precipitation  of  various  kinds  should  be 
measured  by  gauge  during  storms  in  different  seasons.  These  obser- 
vations lead  to  the  following  problems  : — 

a.  The  relation  of  precipitation  in  general  to  the  other  weather 
elements,  and  to  cyclones  and  anticyclones  of  the  weather  maps 
(Davis,  287,  293,  300). 

b.  The  conditions  under  which  special  forms  of  precipitation  (rain, 
snow,  sleet,  hail,  frozen  rain)  occur  (Davis,  285-287). 

c.  The  conditions  associated  with  light  and  heavy,  brief  and  pro- 
longed, local  and  general  rainfall  (Davis,  248,  300). 


12 


VI.  PRESSURE. 

(Instructions,  30-42.  Davis,  82-86.) 

The  variations  of  atmospheric  pressure,  although  insensible  to 
non-instrumental  observation,  are  so  intimately  connected  with 
atmospheric  processes  that  they  deserve  careful  attention.  Their 
observation  leads  to  several  problems  : — 

a.  The  decrease  of  pressure  with  height,  as  between  valley  and 
hill;  or  between  base  and  top  of  a building  (Davis,  87,  88). 

b.  The  diurnal  and  cyclonic  variation  of  pressure  in  different 
seasons  (Davis,  85,  86,  215,  316-318). 

c.  The  relation  of  local  pressure  changes  to  cyclones  and  anti- 
cyclones, and  thus  to  weather  changes  (Davis,  228,  316-318). 


VII.  WEATHER  MAPS. 

(Davis,  319-325.) 

The  use  of  the  weather  maps  in  connection  with  the  problems  of 
the  preceding  sections  should  have  fully  established  the  correlation 
between  local  and  general  conditions  of  temperature,  pressure,  wind, 
and  weather.  Under  the  present  heading,  practice  should  be  given 
chiefly  in : — 

a.  The  construction  of  weather  maps. 

b.  Weather  prediction  by  means  of  weather  maps,  either  used 
alone,  or  supplemented  by  local  observations  (Davis,  324). 

General  Remarks. 

A review  of  the  seven  preceding  headings  will  show  that  a very 
general  correlation  exists  among  them,  whereby  the  subjects  of  every 
heading  are  associated  with  those  of  nearly  every  other.  In  other 
words,  every  weather  element  is  treated  as  a function  of  several 
other  elements.  It  follows  from  this  that  the  variety  of  work  here 
outlined  is  more  apparent  than  real,  and  that  many  problems  which 
appear  from  their  wording  to  be  entirely  new  are  in  large  part 
re-arrangements  of  problems  previously  encountered.  A review  is 
therefore  less  necessary  at  the  end  of  such  a course  as  this  than  it 
might  be  in  a course  where  the  last  heading  was  entirely  unconnected 
with  the  first. 


13 


NON-OBSERVATIONAL  WORK. 

The  non-observational  or  text-book  portion  of  the  course  should 
supplement  the  observational  work.  It  is  intended  to  present  the 
larger  and  more  general  principles  of  meteorology,  which  cannot 
be  gained  through  local  observation,  but  which  serve  to  show  the 
correlation  of  the  various  local  phenomena  with  their  fellows  else- 
where over  the  world.  As  in  the  previous  division  of  the  course, 
much  must  necessarily  be  left  to  the  teacher,  both  as  regards  the 
selection  and  order  of  additional  subjects  presented,  and  as  regards 
the  illustration  of  these  subjects ; but  an  essential  for  the  satisfac- 
tory extension  of  the  course  under  the  present  heading  is  that  the 
topics  here  introduced  should  have  been  first  encountered  more  or 
less  directly  in  the  problems  of  local  observation. 

In  the  following  pages,  reference  is  made  to  appropriate  chapters 
of  the  text-book  ; but  it  is  not  expected  that  the  text  will  be  closely 
adhered  to,  or  that  it  will  be  possible  in  every  case  to  make  the 
course  as  full  as  is  here  suggested. 

Composition  of  the  Atmosphere , and  its  Relations  to  Plants  and 
Animals  (Davis,  Elementary  Meteorology,  Chap.  I). 

In  the  didactic  presentation  of  a science,  where  the  order  of  subjects 
has  little  relation  to  the  questions  asked  by  the  pupils,  this  subject 
usually  stands  at  the  beginning  of  the  course.  In  the  text-book 
supplement  to  an  observational  course,  it  should  be  introduced  only 
after  questions  concerning  it  have  been  raised  by  the  pupils.  The 
expert  teacher  will  have  little  difficulty  in  directing  the  observational 
work  in  such  a manner  that  the  questions  shall  be  called  forth  at 
any  convenient  stage  of  progress. 

Extent  and  Arrangement  of  the  Atmosphere  about  the  Earth 

(Chap.  II). 

This  topic  may  suggestively  follow  the  determination  of  the  de- 
crease of  atmospheric  pressure  with  increase  of  altitude.  Obser- 
vations of  shooting  stars  may  here  be  referred  to,  and  by  corre- 
spondence with  another  school  about  a hundred  miles  distant, 
rough  determinations  of  the  height  of  the  November  meteors 
(November  13)  may  easily  be  made. 


14 


Control  of  Atmospheric  Temperatures  by  the  Sun. — The  relation 
of  the  sun  and  earth,  as  determining  the  distribution  of  insolation 
over  the  earth,  and  its  variations  in  time  and  place ; the  action  of 
insolation  on  air,  water,  and  land ; the  general  idea  of  vertical 
temperature  gradients,  of  local  convectional  circulation,  and  (briefly) 
of  adiabatic  changes  of  temperature  in  vertical  currents  (Chap.  III). 

A few  questions  concerning  the  change  in  the  sun’s  noon  altitude, 
in  the  direction  of  its  rising  and  setting,  and  in  the  length  of  the  day 
on  successive  dates  will  suggest  the  advisability  of  constructing  a 
diagram  of  the  earth’s  orbit  in  true  proportions.  A small  globe 
moved  around  the  orbit  in  proper  position  will  lead  to  a clear  under- 
standing of  the  changes  of  the  seasons,  etc.  This  should  be  fre- 
quently referred  to  during  the  passage  of  the  school  year. 

In  association  with  the  various  observations  on  temperature,  a 
number  of  simple  physical  experiments  may  be  introduced,  illustra- 
ting reflection,  transmission,  absorption,  conduction,  convection ; all 
these  being  repetitions  or  extensions  of  experiments  previously  made 
in  a course  on  Physics.  Diagrams  of  diurnal  and  cyclonic  tempera- 
ture ranges  and  of  vertical  temperature  gradients  from  various  locali- 
ties should  be  introduced  as  a natural  sequence  of  the  results 
determined  by  local  observation. 

General  Distribution  of  Temperature  over  the  Earth.  — Syste- 
matic irregularities  of  isothermal  lines ; effects  of  ocean  currents  on 
the  course  of  isotherms ; thermal  anomalies ; annual  ranges  of 
temperature  on  land  and  water  (Chap.  V,  omitting  sections  73-80). 

These  subjects  naturally  follow  the  determination  of  the  mean 
temperature  of  a day,  of  a period  of  days,  and  of  successive  periods. 
Exchange  of  records  between  schools  standing  on  or  near  the  same 
parallel  or  the  same  meridian  will  prove  suggestive,  both  in  awaken- 
ing and  in  answering  questions.  After  the  establishment  of  this 
course  for  a few  years,  the  comparison  of  current  records  with  those 
of  previous  years  will  be  instructive. 

The  General  Circulation  of  the  Atmosphere. — The  general  move- 
ment of  the  lower  winds  in  different  zones  and  different  seasons ; 
with  a brief  statement  of  the  convectional  theory  of  atmospheric 
circulation  (Chap.  VI,  omitting  sections  93-95,  98-108,  111-113, 
116-123,  128,  131,  and  the  greater  part  of  Chap.  VII). 


15 


The  prevailing  movement  of  the  upper  air  currents  from  the  west 
over  all  parts  of  the  United  States  will  he  detected  after  a few  weeks 
of  observation.  The  determination  of  the  prevailing  westerly  source  of 
the  surface  winds  will  generally  require  a little  longer  interval.  These 
two  facts  suffice  to  introduce  a description  of  the  prevailing  direc- 
tions of  atmospheric  movement  in  other  parts  of  the  world,  thus 
quickly  leading  to  their  systematic  classification.  It  is  important 
that  the  explanation  of  the  general  circulation  of  the  atmosphere,  as 
modified  by  the  earth’s  rotation,  should  be  touched  upon  lightly, 
as  its  real  nature  is  too  difficult  for  elementary  presentation.  The 
wind  belts,  their  migration,  and  their  modification  by  continental 
interruptions,  offer  plentiful  material  for  this  part  of  the  course. 

Humidity , Dew , Frost , and  Clouds. — The  moisture  of  the  atmos- 
phere ; evaporation,  absolute  and  relative  humidity,  dew  point,  con- 
densation on  solid  or  liquid  surfaces  or  in  the  air ; classification  of 
clouds  (Chap.  VIII,  omitting  sections  174-176;  Chap.  IX,  omitting 
sections  191,  192,  198). 

A variety  of  physical  experiments  illustrative  of  the  evaporation 
and  condensation  may  be  here  introduced.  Observations  during  a 
few  successions  of  fair  and  cloudy  days  will  serve  to  arouse  all  the 
questions  here  needed.  The  geographical  distribution  of  these 
topics  is  considered  under  later  headings. 

Storms.  — Cyclones  and  Anticyclones  and  their  Associated  Winds  ; 
Thunderstorms  and  Tornadoes  (Chap.  X,  omitting  sections  239, 
247 ; Chap  XI). 

The  correlation  of  local  observation  with  the  winds  charted  on 
weather  maps  will  suffice  to  introduce  the  greater  part  of  these  topics  ; 
the  text-book  may  then  supply  fuller  information  about  the  circula- 
tion of  winds  in  cyclones  and  anticyclones,  the  occurrence  and  paths 
of  cyclones  in  various  parts  of  the  world,  their  relation  to  the  general 
circulation,  the  peculiar  winds  associated  with  them,  etc.  An 
account  of  local  storms  may  be  introduced  after  a thunderstorm 
ordinarily  observed  in  the  later  months  of  the  school  year ; or  if 
then  wanting,  the  newspaper  reports  of  local  storms  during  the 
spring  may  be  utilized  to  introduce  these  topics  : their  explanation 
may  then  be  briefly  treated. 

Causes  and  Distribution  of  Rainfall  (Chap.  XIII):  — The  cor- 
relation of  rainfall  with  stormy  disturbances  and  with  the  general 


16 


circulation  of  the  atmosphere  gives  the  best  clue  to  its  general  dis- 
tribution and  seasonal  variation  over  the  world. 

Weather  and  Weather  Prediction  (Chap.  XIII)  : — Throughout 
the  whole  of  the  observational  work,  there  will  be  abundant  oppor- 
tunity of  introducing  various  topics  under  this  heading.  The  vari- 
able weather  characteristic  of  nearly  every  part  of  the  United  States 
should  be  compared  with  the  similarly  variable  weather  of  certain 
other  regions,  and  contrasted  with  the  more  uniform  weather  of  the 
greater  part  of  the  torrid  zone  and  of  certain  sub-tropical  sea-coasts. 

Climate  (Chap.  XIV): — The  succession  of  the  seasons  and  the 
distribution  of  various  kinds  of  weather  through  the  year  leads 
naturally  to  a study  of  those  recurrent  atmospheric  conditions  which 
constitute  climate.  The  climates  of  various  zones  and  regions  may 
then  be  introduced  as  like  or  unlike  our  own  climate.  Here  the  de- 
pendence of  human  opportunities  upon  atmospheric  controls  is  best 
introduced,  although  reference  to  this  important  subject  may  be  made 
in  connection  with  various  earlier  headings. 


